Electric cooling fan

ABSTRACT

An axial fan has a hub supporting blades. The hub is attached to a rotor of an electric motor at one or more points of connection by respective connecting devices. Each connecting device includes an annular damper, arranged in an opening of the hub, and through which a screw passes. Placed between the damper and the screw is a rigid element having one end resting against the rotor. The other end has an annular flange-like formation disposed between the damper and a head of the screw. The rigid element has an annular skirt which extends from the flange-like formation, around the damper, up to a preset distance from the hub of the fan, such that when the fan performs an oscillation greater than a predetermined extent, it impacts this skirt thereby limiting its oscillation.

CROSS REFERENCE TO RELATED APPLICATIONS

This non-provisional patent application claims priority under 35 U.S.C. §119(a) from Patent Application No. TO2014A000321, filed in Italy on Apr. 15, 2014, the entire contents of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to an electric cooling fan, particularly for a heat exchanger (such as a radiator) of a motor vehicle.

BACKGROUND OF THE INVENTION

More specifically, a subject of the invention is an electric fan of the type comprising: an electric motor including a rotor and a stator, and an axial fan, with a central hub from which there extends a plurality of blades and which is connected to the rotor of the motor at one or more points of connection. At the or each point of connection, the hub of the fan is connected to the rotor by a respective connecting device. The or each connecting device has an annular damper of elastic material arranged in an opening of the hub and through which a fastening member passes. Between the damper and the fastening member is a rigid element having one end resting against the rotor. The other end of the rigid element has an annular flange-like formation which rests against the damper at the side opposite the rotor.

According to such a solution, the use of connecting devices including dampers of elastic material provides for reducing the intensity of the vibrations transmitted from the motor to the fan and, consequently, for reducing the generation of acoustic noise that is annoying for the human ear, particularly at low speeds.

The presence of elastic dampers however makes the connection of the fan to the rotor of the drive motor less rigid. Some tests provided by motor vehicle manufacturers require that the fan can perform only oscillations of extremely limited extent, in particular even when the motor vehicle on which the electric fan is installed is subjected to angular accelerations of extremely high extent, to avoid contact between the fan and stationary parts near the fan.

Hence there is a desire for an electric fan able to meet such stringent requirements.

SUMMARY OF THE INVENTION

Accordingly, in one aspect thereof, the present invention provides an electric cooling fan comprising: an electric motor including a rotor and a stator, and an axial fan, with a central hub from which there extends a plurality of blades and which is connected to the rotor of the motor at one or more points of connection, at the or each point of connection, the hub of the fan being connected to the rotor of the motor by means of a respective connecting device including a vibration damper, arranged in an opening of the hub, and through which a fastening member passes, there being placed between the damper and the corresponding fastening member a rigid element having one end resting against the rotor and the other end which has an annular flange-like formation resting against the damper at the side opposite the rotor; wherein the rigid element has an annular skirt which extends from the flange-like formation, around the damper, to a preset distance from the hub, in such a way that when the fan performs, with respect to the rotor, an oscillation greater than a predetermined extent, the hub impacts the skirt thereby limiting the extent of the oscillation.

Preferably, the hub of the fan has a substantially cup-like shape, with a base wall connected with an annular side wall, and the rotor has a cap which extends inside the hub, close to the base wall to which it is connected by means of a plurality of connecting devices including respective vibration dampers.

Preferably, the annular side wall of the hub is at least approximately cylindrical.

Preferably, the vibration damper is annular.

Preferably, the damper is of elastic material.

Preferably, the elastic material is vulcanized rubber.

Preferably, the damper is substantially in the shape of a cylindrical ring, and has an outer peripheral groove into which the edge of the through-opening of the hub is engaged.

Preferably, the fastening member is a screw or bolt, having a head which presses on the flange formation of the rigid element.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will now be described, by way of example only, with reference to figures of the accompanying drawings. In the figures, identical structures, elements or parts that appear in more than one figure are generally labeled with a same reference numeral in all the figures in which they appear. Dimensions of components and features shown in the figures are generally chosen for convenience and clarity of presentation and are not necessarily shown to scale. The figures are listed below.

FIG. 1 is a front perspective view of an electric cooling fan according to the invention;

FIG. 2 is a partial perspective view, in enlarged scale, which shows in particular the hub of the fan of the electric fan; and

FIG. 3 is a partial view in cross-section along the line of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the drawings, an electric cooling fan according to the present invention is indicated as a whole with the reference 1. The electric fan 1 comprises, in a known way per se, a substantially plate-like support structure or shroud 2, exhibiting a circular main opening 3 at which there is rotatably fitted a fan indicated as a whole with the reference 4.

The fan 4 is connected to the rotor of an electric motor which is not visible in FIGS. 1 and 2, but is partially illustrated in FIG. 3, in which it is indicated as a whole with the reference 5. The electric motor 5 comprises a stator 6, fixed in a known way per se to the support structure or shroud 2, for example by means of a plurality of spokes indicated with the reference 7 in FIG. 1. The electric motor 5 additionally comprises the rotor, including a cap, indicated with the reference 8 in FIG. 3.

The fan 4 comprises a central hub 9, from which there extends a plurality of curved blades 10, the outermost extremities of which meet a peripheral ring 11 as shown in FIG. 1. The hub 9 of the fan 4 is connected to the rotor 8 of the electric drive motor 5 at one or more points of connection 12. It should be realized that the term connection point or point of connection may not be necessarily a single point and may include a connection area, in accordance with the type of fixation method or fastening member used.

In the embodiment illustrated, the hub 9 is connected to the cap of the rotor 8 at three points of connection 12, located at a same distance d from the axis X-X of the fan (FIG. 3).

In the embodiment illustrated, the hub 9 of the fan 4 exhibits a substantially cup-like shape, with a base wall 9 a connected with an annular side wall 9 b, which is at least approximately cylindrical. The cap of the rotor 8 extends inside the hub 9, close to the base wall 9 a to which it is connected at the three points of connection 12 by connecting devices 13 including respective elastic vibration dampers, which will be better described below.

With reference in particular to FIG. 3, each connecting device 13 comprises an annular damper 14, of elastic material, in particular of elastomeric material (vulcanized rubber). Each damper 14 is arranged in a respective through-opening 9 c of the base wall 9 a of the hub 9 of the fan. The damper 14 is substantially in the shape of a cylindrical ring, and in its axially intermediate part has an outer peripheral groove 14 a into which the edge of the through-opening 9 c is engaged.

A corresponding fastening member 15 of the fan passes through the damper 14 and the rotor cap. The fastening member 15 is for example a screw or a bolt, and is provided with a head 15 a which presses the damper against the rotor cap. Preferably the fastening member 15 engages the rotor cap by a threaded connection. That is, the screw or bolt is screwed into the rotor cap.

Between the annular damper 14 and the screw or bolt 15, there is placed a tubular element 16 of substantially rigid material, such as for example a metal material. The rigid tubular element 16 conveniently has an end flange formation 16 a, placed between the head 15 a of the screw or bolt 15 and the adjacent end of the damper 14. The threaded stem of the screw or bolt 15 engages in a correspondingly threaded opening of the rotor cap 8.

The rigid element 16 moreover has an annular skirt 16 b which extends from the flange-like formation 16 a, around the damper 14, to a preset distance from the hub 9 of the fan 4.

The arrangement is such that when the fan 4 performs an oscillation, relative to the rotor 8, greater than a predetermined extent, the hub impacts the edge of the bottom end of the skirt 16 b, thereby limiting its oscillation.

The maximum extent of oscillation allowed at the fan 4 is determined by the distance z between the bottom edge of the skirt 16 b and the surface of the hub 9.

The solution described above provides for meeting the requirement mentioned at the start of the present description.

In the description and claims of the present application, each of the verbs “comprise”, “include”, “contain” and “have”, and variations thereof, are used in an inclusive sense, to specify the presence of the stated item or feature but do not preclude the presence of additional items or features.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

Naturally, the principle of the invention remaining the same, the forms of embodiment and details of construction may be varied widely with respect to that which has been described and illustrated purely by way of non-limiting example, without thereby departing from the scope of the invention as defined in the appended claims. 

1. An electric cooling fan comprising: an electric motor including a rotor and a stator, and an axial fan, with a central hub from which there extends a plurality of blades and which is connected to the rotor of the motor at one or more points of connection, at the or each point of connection, the hub of the fan being connected to the rotor of the motor by means of a respective connecting device including a vibration damper, arranged in an opening of the hub, and through which a fastening member passes, there being placed between the damper and the corresponding fastening member a rigid element having one end resting against the rotor and the other end which has an annular flange-like formation resting against the damper at the side opposite the rotor; wherein the rigid element has an annular skirt which extends from the flange-like formation, around the damper, to a preset distance from the hub, in such a way that when the fan performs, with respect to the rotor, an oscillation greater than a predetermined extent, the hub impacts the skirt thereby limiting the extent of the oscillation.
 2. The electric fan of claim 1, wherein the hub of the fan has a substantially cup-like shape, with a base wall connected with an annular side wall, and the rotor has a cap which extends inside the hub, close to the base wall to which it is connected by means of a plurality of connecting devices including respective vibration dampers.
 3. The electric fan of claim 2, wherein the annular side wall of the hub is at least approximately cylindrical.
 4. The electric fan of claim 1, wherein the vibration damper is annular.
 5. The electric fan of claim 1, wherein the damper is of elastic material.
 6. The electric fan of claim 5, wherein the elastic material is vulcanized rubber.
 7. The electric fan of claim 1, wherein the damper is substantially in the shape of a cylindrical ring, and has an outer peripheral groove into which the edge of the through-opening of the hub is engaged.
 8. The electric fan of claim 1, wherein the fastening member is a screw or bolt, having a head which presses on the flange formation of the rigid element. 